1. Field of the Invention
The present invention relates to a hammer and a keyboard system and, in particular, to a hammer having a simplified structure and reduced costs and that maintains its capability as a mass body to impart a touch weight. The present invention also relates to a keyboard system comprising the hammer. In addition, the present invention relates to a chassis and, in particular, to a chassis in which the chassis main body and the control member are formed as a single unit and with which it is possible to miniaturize the design of the electronic musical instrument overall.
2. Description of Related Art
For some time, hammers have been installed in keyboard systems that are used in electronic pianos and the like. These hammers are provided for each key (for example, 88 keys) and are configured such that, when a key is pressed or released, because the corresponding hammer is linked to the key and swings, a touch weight is imparted that is the same as that for an acoustic piano.
With this kind of hammer, the arrangement of the layout must be limited to the space in the keyboard system, and the hammers are required to be formed in relatively complex shapes. In addition, weight is also needed in order for the hammer to function as the mass body that imparts the touch weight. Because of this, the hammer is furnished with a hammer main body constructed from a resin molding, which has a comparatively large degree of freedom for the shape and a load constructed from a metal material having a high relative density, enabling the weight to be increased. It is normal for the configuration to be such that the load is attached to the tip of the hammer main body.
Here, as the structure for the attachment of the load to the hammer main body, the method is known with which the weight is fixed to the hammer main body by means of riveting. For example, in Japanese Unexamined Patent Application Publication (Kokai) Number 2000-122652, a hammer is cited in which two mass plates (loads) are attached to the left and right attachment surfaces of the hammer main body so as to sandwich the hammer main body between them. By means of this hammer, after concave portions in both mass plates are aligned with protrusions on each of the attachment surfaces of the hammer main body and the plates are positioned, rivets are driven into each of the two rivet holes that have been drilled into the hammer main body and both mass plates. Thus, by this means, the two mass plates are fixed to the attachment surfaces of the hammer main body (Patent Reference 1).
In addition, it is usual for keyboard systems that are used with electronic pianos and the like to be configured with a chassis, a plurality (for example, 88) of keys that are supported axially so that they swing and that are lined up and disposed on the chassis in the left-right direction, and a plurality of hammers that are linked to the pressing or releasing of each of the keys and, by swinging, impart a touch weight that is the same as that of an acoustic piano. Here, it is necessary that the chassis be provided with a support section for supporting the keys and the hammers, making it possible for them to swing, and a control member that controls the swinging of the keys and the hammers, which swing due to the pressing or releasing of the keys. Alternatively, a guide member can be provided that guides the keys in the up and down direction at the time of pressing or releasing. For example, in Japanese Unexamined Patent Application Publication (Kokai) Number 2000-122852, a technology is cited in which the unit is furnished with a connecting bar that connects and fixes a chassis that has been divided in the left-right direction. The connecting bar forms the control member discussed above (Patent Reference 1).
Specifically, on each of the chassis, which have been divided into a plurality in the left-right direction, is respectively formed a support section that supports the keys on the rear edge section, a support section that supports the hammers on the center section, and a guide member that guides the keys on the front edge section. The front edges and the rear edges of each chassis are connected and fixed by a long shaped connecting bar. In addition, the bottom portion of the connection bar that connects and fixes the front edges of each chassis forms the control member that controls the lower limit of the swinging of the hammers.
However, with the attachment structure discussed above, it is necessary to drive high-cost rivets into a multiple number of places and the component count increases. In addition, since it is not possible to position each of the mass plates in the circumferential direction with respect to the hammer main body using only the alignment of the protrusions used for positioning and the concave portions, special work is required to position each of the rivet holes with the others. As a result, component and assembly costs increase because of the increase in the component count as well as the added complexity of the attachment work, and the product cost of the hammer overall rises.
Because of the plastic processing ability at the time of caulking, rivet metal having a comparatively low relative density such as aluminum and the like is used. Thus, when the number of locations in which the rivet holes are drilled in the mass plates is in proportion to the number of rivets employed, the weight of the hammer overall is lightened by that amount and it is not possible for the function of the mass plates that impart the touch weight to be fully manifested. In that case, the necessity arises to make the mass plates larger so as to maintain the required weight. This leads to the enlarging of the hammer overall.
In addition, with the chassis structure discussed above, since the connecting bar and the guide member are disposed on the front edge of the chassis, there is the problem that the space for arranging the wiring (the electrical cabling) and the edge plate (the wooden plate that is disposed below the front edge of the white keys) and the like is reduced by that amount. As a result, when the electronic musical instrument is assembled, the wiring and the edge plate protrude further outward than the front edge of the white keys by the amount for the disposition of the connecting bar and the guide member. Thus, the electronic musical instrument becomes larger and its appearance is blemished.
In addition, when the connecting bar and the guide member are arranged on the front edge of the chassis in this manner, the position for the arrangement of the hammers must be shifted toward the rear edge of the chassis; since the chassis is extended toward the back, the electronic musical instrument becomes enlarged by this amount also.
The present invention solves the problems discussed above and has as its object the provision of a hammer and a keyboard system that has a simplified hammer structure and, while designing for a reduction in the component and assembly costs, maintains the capability of the mass body to impart a touch weight. In addition, it has as its object the provision of a chassis in which the chassis main body is molded in a single unit with the control member and that makes possible the reduction in size of the electronic musical instrument.